Let's let the variable x represent one of the numbers.
Since the other number of 7 less than the other, we can write the following expression to represent the other number: x - 7
Also since the sum of the two numbers is 17, we can write the following equation:
x + x - 7 = 17
Now solve for x by combining like terms and using inverse operations:
x + x - 7 = 17
2x - 7 = 17
2x - 7 + 17 = 17 + 7
2x = 24
2x/2 = 24/2
x = 12
Therefore one number is 12 and the other is 12 - 7 or 5
Note that their sum is 17 (12 + 5 =17).
